1. Field of the Invention
The present invention relates generally to submersible or harsh environment electrical or electro-optical connectors which can be mated and unmated in a harsh environment, such as underwater, and is particularly concerned with a secondary sealing device for such connectors.
2. Related Art
There are many types of connectors for making electrical and fiber-optic cable connections in hostile or harsh environments, such as undersea or submersible connectors which can be repeatedly mated and demated underwater at great ocean depths. Current underwater connectors typically comprise releasably mateable plug and receptacle units, each containing one or more electrical or optical contacts or junctions for engagement with the junctions in the other unit when the two units are mated together. The contacts on one side are in the form of pins or probes, while the contacts or junctions on the other side are in the form of sockets for receiving the probes. Typically, the socket contacts are contained in a sealed chamber containing a dielectric fluid or other mobile substance, and the probes enter the chamber via one or more sealed openings. One major problem in designing such units is the provision of seals which will adequately exclude seawater and/or contaminates from the contact chamber after repeated mating and demating.
In some known underwater electrical connectors, the receptacle unit has a stopper which is positioned in sealing engagement with an annular end seal when the units are not mated. The chamber sealed by the stopper and end seal contains a circuit contact and dielectric mobile substance. The receptacle unit may have one such contact chamber or plural contact chambers each sealed by respective stoppers in the end seal, depending on the number of connections to be made. As the plug probe enters the chamber, it pushes the stopper back, enters the inner chamber, and makes electrical contact with the circuit connection. At the same time, the end seal will seal against the plug probe to ensure that water cannot enter the chamber. This provides a robust and reliable electrical connector for use in deep sea or other harsh environments. Such connectors are generally known as pin-and socket type connectors and one such connector is described in U.S. Pat. No. 5,645,442 of Cairns. This connector is manufactured and sold by Ocean Design, Inc. under the name Nautilus®. U.S. Pat. No. 6,332,787 of Barlow et al. describes a similar electrical connector arrangement in an electro-optical connector for connecting both electrical and optical circuits.
In a pin-and-socket connector, each plug pin or probe has an elongated shaft enclosed in a dielectric sheath along most of its length, with an exposed conductive tip which contacts the corresponding electrical socket contact in the mated condition. The probe or pin projects forwardly from a dielectric base member in the plug unit so that at least part of the body of the probe is exposed to the surrounding environment when the connector units are unmated. When the pin engages in the contact chamber of the mating receptacle unit, the contact chamber is sealed by the sealing engagement of the end seal with the dielectric sheath of the plug pin or probe.
One problem with such connectors is that the front portion of any electrical pin is partially exposed to seawater in the fully mated condition, potentially increasing electrical stress, and also resulting in degradation of exposed parts of the pin due to extended exposure to seawater.